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Issue 866924 link

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Issue metadata

Status: Fixed
Owner:
Closed: Jul 24
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Linux , Windows , Mac
Pri: 1
Type: Bug



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Disabling "enable-webassembly-baseline" does not really disable Liftoff

Project Member Reported by clemensh@chromium.org, Jul 24

Issue description

In V8, we still have an ordering problem with processing flags. In this
case, the "--wasm-tier-up" flag implies "--liftoff", and since
"--wasm-tier-up" is enabled by default, also "--liftoff" is enabled by
default.
If if "enable-webassembly-baseline" is explicitly set to "disabled", we pass "--no-wasm-tier-up" via {SetFlagsFromString}, which correctly disables tier up, but since the implications were already applied before that, the "--liftoff" flag stays enabled.

Fix is here: https://crrev.com/c/1148386

This will have to be merged to M-69, requesting that right away. It's an extremely low-risk fix which should make it to the beta release.

Setting release blocker, as without this fix we cannot disable Liftoff via Finch, and we don't want to launch without that option.

Anyone with the power to do so, feel free to land the CL right away and merge it back to M-69 (via v8's merge process).
 
Correction of the last sentence: This is a chromium CL, so would need to be merged via chromium's process :)
Project Member

Comment 2 by bugdroid1@chromium.org, Jul 24

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fab5510cbf8165739f2d228ba6d4c25c5b5530f8

commit fab5510cbf8165739f2d228ba6d4c25c5b5530f8
Author: Clemens Hammacher <clemensh@chromium.org>
Date: Tue Jul 24 16:19:19 2018

[Flags] Explicitly disable Liftoff if tier up is disabled

In V8, we still have an ordering problem with processing flags. In this
case, the "--wasm-tier-up" flag implies "--liftoff", and since
"--wasm-tier-up" is enabled by default, also "--liftoff" is enabled by
default. If we now set "--no-wasm-tier-up" (via {SetFlagsFromString}),
this does not disable "--liftoff". Hence, disable it explicitly.

R=jochen@chromium.org, titzer@chromium.org

Bug:  chromium:866924 , chromium:787421
Change-Id: I298792bda07ef02a8f039c72be165ec815baa46f
Reviewed-on: https://chromium-review.googlesource.com/1148386
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577571}
[modify] https://crrev.com/fab5510cbf8165739f2d228ba6d4c25c5b5530f8/content/renderer/render_process_impl.cc

Labels: Merge-Request-69
Status: Fixed (was: Started)
Project Member

Comment 4 by sheriffbot@chromium.org, Jul 25

Labels: -Merge-Request-69 Hotlist-Merge-Approved Merge-Approved-69
Your change meets the bar and is auto-approved for M69. Please go ahead and merge the CL to branch 3497 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), kariahda@(iOS), cindyb@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot
Pls merge your change to M69 branch 3497 latest by 3:00 PM PT today, Wednesday (07/25/18). Thank you.
Backmerge CL here: https://crrev.com/c/1150380
Waiting for committer/owner LGTM.
Project Member

Comment 7 by bugdroid1@chromium.org, Jul 26

Labels: -merge-approved-69 merge-merged-3497
The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f48932797bc3447281a4d389f725362328cde84b

commit f48932797bc3447281a4d389f725362328cde84b
Author: Jochen Eisinger <jochen@chromium.org>
Date: Thu Jul 26 07:50:09 2018

[Flags] Explicitly disable Liftoff if tier up is disabled

In V8, we still have an ordering problem with processing flags. In this
case, the "--wasm-tier-up" flag implies "--liftoff", and since
"--wasm-tier-up" is enabled by default, also "--liftoff" is enabled by
default. If we now set "--no-wasm-tier-up" (via {SetFlagsFromString}),
this does not disable "--liftoff". Hence, disable it explicitly.

R=jochen@chromium.org, titzer@chromium.org
TBR=clemensh@chromium.org

(cherry picked from commit fab5510cbf8165739f2d228ba6d4c25c5b5530f8)

Bug:  chromium:866924 , chromium:787421
Change-Id: I298792bda07ef02a8f039c72be165ec815baa46f
Reviewed-on: https://chromium-review.googlesource.com/1148386
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#577571}
Reviewed-on: https://chromium-review.googlesource.com/1150380
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/branch-heads/3497@{#101}
Cr-Branched-From: 271eaf50594eb818c9295dc78d364aea18c82ea8-refs/heads/master@{#576753}
[modify] https://crrev.com/f48932797bc3447281a4d389f725362328cde84b/content/renderer/render_process_impl.cc

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